Routers in packet switched networks generally employ one or more network processors, typically an application-specific integrated circuit (ASICs), to perform various packet processing operations. Each network processor is generally associated with a plurality of media access controllers from which frames are received and to which frames are transmitted. Historically, the routers were designed so that the network processor could simultaneously accommodate traffic from each of the associated ports being operated at its designated wire speed, typically 100 or 1000 megabits/sec. There is, however, a trend to over-subscribed ports, meaning that the bandwidth of the network processor or other router resources is generally unable to support each of the ports operating at wire speed for a sustained period of time. While the per-port cost savings for an over-subscribed system provides a beneficial tradeoff for some customers, oversubscribing ports may lead to some loss of data as a result of the inability of the network processor or route processor to handle the traffic.
In order to minimize the detrimental effects of over-subscription, routers may employ extensive buffering in an attempt to capture bursts of traffic until the resources are available to processes the traffic. Pause messages may also be transmitted to one or more link partners to temporarily reduce the amount of data received and thereby reduce the chance of buffer overflow. Despite limited success, both of these approaches fail to address the underlying inability of the network processor or other resources to handle large volumes of traffic. There is therefore a need for a means of maintaining the advantages of oversubscribed port configurations while reducing the computational demands on the network processor.